Electric switch



Aug. 1, 1939. A. 5 GRANT ELECTRIC swmm 3 Sheets-Sheet 1' Filed Oct. 223, 1935 INVQNTOR Alb Z 5 Grani ATORNEY Aug. 1, 1939. A. E. GRANT ELECTRIC SWITCH s Sheets-Shet 2 Filed 001;. 25, 1955 w a a H d f|i. 1 a w m fiw 5 2 a 9L a 0 a 1 2 WW 2 ozw w V v/V/Vi 3% 2w 4 5 VIII/I746. .4 n 6 any- M fiu m *M I; l J 1 o "M 0 HI WW PU u m a J4 3 w W "W 6 PM @lv 2 4 W 6% y 7 5w 2 MM 6 A. E. GRANT Aug. 1,' 1939.

ELECTRIC SWITCH Filed Oct. 25, 1935 3 Sheets-Sheet 3 INVENTOR 62% E. 612ml ATTORNEY Patented Aug. 1 I

um'rsp 's'rA'rss. PATENT OFFICE ELECTRIC SWITCH Albert a. Grant, New Yorh, N. Y., can... by

direet-andmesne assignments,toAlber-t T. Otto. & Sons, Inc., New York, N. Y., trustee Application mm :5, ms, Serial No. 40,641;

a cum (on. zed-11a) My invention relates to electric switches of I showing the relationship of the, parts when the ij the-type that are actuated to break a circuit by resetting operation has been completed and the anoverload of current. A principal object oi spring pressedswitch element hassnapped into invention is to provide an improved switch. briiking position to complete the circuit.

I of this character incorporating a novel mechani- Figure. 15 is a sectional view of the parts com- I cal movement whereby the movable bridging eleprising the switch mounting,- takenon linel5-IU mentpoi the switch mechanism comprises a cam of Figure 12. and is pivotedin a manner to change its fulcrum Figure 16 is a perspective view of the cammed as .it isreset to avoid contact with the switch switch member and integral resetting lever.

terminals during the resetting movement. An- Figure 17 is a perspective view of the post on 10 other object is to provide such a mechanical which the switch member '-.is mounted.

movement. Figure 18 is a schematic view illustrating the My novel-switch mechanism may be advantacircuit through the device. seep-sly. emhodiedin aplug device designed to re- The internal parts of. the device are mounted Place the usual screw type fuse plug. Another on a base fl of porcelain brother similar insuobject of my invention, therefore, is to provide lating material and are encased by a housing 2| 1 all-improved plug-type switch or circuit breaking of insulating plastic. The base and the housing which: will automatically and instantly are held together in assembled relation by break. an overloaded circuit-and which may be screw shell contact 23' which is. flanged at its m readil reset to perform its function an indeil- .lower periphery to engage under a .shoulder 22 go nite, number of=times without replacement. A fur-. formed on the base. The contact carries flanged therpbiect-is to provide a device of this nature integral lugs 24 which extend through slots in which will be simple in construction, inexpensive the casing wall and are clenched against the into manufacture and which will afford protection ner surface thereof. thereby holding the base and II to the user against-"shock when coupling or unthe body portionoi' the housing permanently as coupling this device in circuit in anordinary fuse assembled.

box. The walls of the housingat the lower portion Other andfurther objects will appear from the thereof are circular and coincide with the upper following specification. flanged edgefiof the base The upper portion 80 -.-.Referring'to=the drawings, all of which illusof" the housing is substantially rectangular or so trate the deviceon a scale larger than actual obround to afford iiat surfaces 25 on opposite size: sides of the device whereby it may be conven- Figure 1 is an elevational view of a circuit iently grasped when the device is being inserted breaking device embodying my improved switch or removed from a screw socket. Projecting from mechanism. 1 the flat sides of the casing intermediate its length 35 Figure 2 is an elevational view of the device are semi -circular flanges 26 which form a protaken at right angles to- Figure 1. 7 tective'apron for the fingers of the user when Figure 3. is a plan view and coupling or uncoupling the plug in a fuse box.

Figure Nisan inverted plan view of the device. Formed and proportioned as above described 40 J'lgures 5 to 10 inclusive are sectional views of the housing aiiords the very convenient grips and 40 the device takenonlthe lines indicated by their apron shield for the fingers and may be readily respective :flgure numbers. and advantageously adapted to encase plug parts Figure. 1-1 is a schematic view. of the movable or fuse parts other than those about to be deelement of the switchmember and the parts scribed.

supportingitin relation 'to-the terminals which it The upper end of the housing is sealed by a 46 is adapted. to bridge -in.-circuit, and shows the cover 21, ismortised into the housing wall, as relationship-of the parts when the circuit is shown. and has a slot formed therein at 28 broken- '1 through which the reset button 53 of the switch Figure '13 is a view similar to Figure 11 showmay project. 7

ing-therelgtionship of the parts ata middle stage The base 2. is recessed inwardly from its side 50 of the'lresetting operation. below the shoulder 22' at 29 (see Fig; 6) and a Figure 1am; another similar view showing the metal strip 30 is secured to the base within the relationshipoi the-partsat the final stage of the recess and extends over the shoulder 22 to con-' m v en tact iirmly with the screw contact 23. The strip more 14 its further view similar to Figure 11 3. is secured in position by the lower end of an is eyelet 3|, the upper end of which secures a conductor 32 within the casing. The conductor 32 is made of light conducting spring metal, such as phosphor bronze, and extends upwardly within the casing, its upper free end being inwardly bent, substantially as shown, to form ,a shelflike switch terminal 33.

The other switch terminal 34 consists of the angularly bent free end of a bi-metallic'conductor 35. This latter conductor comprises a thermostatand its lower bent end is secured by an eyelet 36 in a pocket formed in the base 20. The eyelet 36 also secures the lower end of a heating element 31 in firm contacting'relation with the thermostat.

The heating element is composed of resistance wire, such as nichrome alloy,'which is wound in fiat coils extending parallel and in close adj acence to the thermostat and to a wall 40 projecting upwardly from the top of the base 20 into thehousing. The upper end of the heating element is secured to the upper end of a central contact member 38 which extends through the base and projects exteriorly thereof at 38'.

The switch terminals are'adapted to be bridged by a spring pressed element 5| which is supported by the bi-metalterminal 34 and contacts against 7 the light resilient shelf-like terminal 33. It will therefore be apparent that the circuit through the plug will pass through contact 38, traverse the heating element and thermostat to the terof the pocket 20' and by the wall 40, causing the bi-metal to warp away from its supporting position under the spring pressed switch member whereupon the switch member will deflect the light terminal 33 out of its path its bridging position. I

The switch mechanism is mounted on a strip support 42 secured to the base 20 by eyelet 43. The upper end of the support is of reduced breadth and angularly bent to form an arm 44'. Below the arm and extending parallel thereto the support carries a .transverse pivot post 45 on which the moving parts of the switch mechanism are rotatably mounted (see Fig. 15) Separated from the support by a washer 46 is a switch member 50, formed, as shown in Figure 16, to comprise a bridging element 5| at one end and a lever 52 projecting angularly from the other end thereof for manually setting or resetting the switch, the endof the lever being capped by a rounded button 53 fused or otherwise secured thereto. 7 r V Y The switch member is slotted intermediate its length at 54 whereby it is pivotally and slidingly mounted on the post and its edge is contouredto define a double cam, being cams 55 and '56 respectively, the latter being formed in-theangle defined by the projecting lever portion 52 and both being positioned and adapted to ride against arm 44.

Mounted on the post outwardly-of the switch member is a sleeve 53 having its inner end flanged and drop from to form a seat for the innermost convolution of torsion spring 60, the outer end of which is anchored to a horseshoe nut 6| pinched around the post adjacent its end, the post being slabbed to receive the nut as shown (Figure 15).

The inner end of the torsion spring is extended from the coil to form a spring finger 65 overlying the bridging element 5lwhereby the element is urged downwardly at all times, tending to pivot the switch member about the post 45 with the end margins of the slot 54 nearest the switch terminals in engagement with the pivot post, as shown in'Figure 11.

To set or reset the switch, the button 53 is wiped downwardly sidewise from its projecting position above the cover 21 (Figures 1-3) until it is substantially flush therewith, whereupon the finger of the user will be caused to slip from its engaging position. The first stage of this-movement is a simple'pivot causing the bridging element to swing upwardly above the terminals 33 and 34 in spaced .relation thereto, until the cammed edge 56 of the switch member engages the arm 44, as shown in Figure 12. During the second stage of the pivoting movement the cam 56 rides against the arm and the member is thereby caused to walk bodily in the direction of the terminals, sliding to change its fulcruming point to the oppositeend margins of the slot and assuming the position indicated in Figure 13. The finger of the user than releases the actuator button and the member is forced to move in a reverse direction by the spring 60, this reverse movement being a simple pivot which is interrupted when the element 5| snaps into bridging contact on the switch terminals to complete the circuit, as indicated in Figure 14.

In operation, whenever an overload of current causes the element 31 to generate any appreciable heat, suchheat radiates and is reflected against the side of the thermostat most closely adjacent, causing the -bi-metal to be deflected from its supporting position under the bridging element thereby releasing the switch member whichis snapped downwardly by the spring,

brushing the light resilient terminal 33'out of its path and breaking the circuit.

In an early stage of this circuit breaking movement, the cam rides against the arm 44 and the switch member is thereby caused to slide bodily in a direction away from the terminals,

normal position, the switch may be reset, as

heretofore described, to complete the circuit.

again. In this manner the device may be used in place of the usual, fuse plug and will serve to protect the circuit a large and indeterminate number of times.

It will be notedthat practically no strain whatever is placed upon the bi-metallic thermostat conductor which operates merely as a trip for the switchand not as an actuator therefor.

The pivoting switch'mechanism embodying the double cam and link mounting is believed to comprise an entirely novel mechanical movement, in

dependently useful whenever it may be desired to spring pressed switch anda heating element, said provide a member adapted to pivot gthrough difierent paths in opposite directions.

The foregoing description taken in connection with the accompanying drawings discloses the principles oi'a switch mechanism and of a eucuit breaking device which will be readily understood by those skilled in the art to which the invention appertains and comprises what I now consider to be the best embodiment thereof. I

desire to have it understood, however, that the structure shown is merely illustrative and that such changes and adaptations may be made,

when desired, as fall within the scope of the here appended claims.

I claim:

1. A screw plug of the character described comprising acasing and contacts carried thereby exteriorly thereof, a -bi-metallic thermostat within the casing, a switch terminal carried by said thermostat, means within the casing connecting said contacts in circuit, said means comprising said the'rmostatfia stationary, heating element and aswitch member supported by said terminal; the arrangement being such that heat generated by said element will be radiated and directly reflected by the walls of' the pocket.-

against the thermostat and cause the thermostat to deflect and. move said terminal from its supporting position to release the switch and break the circuit.

2. A screw plug of the character describedcomprising a casing having a body portion and contacts carried by the body portion exterior-ly thereof, said body portion having a pocket formed in an interior wall thereof, a iii-metallic thermostat within the casing having one end secured in said pocket and a switch terminal carried by the thermostat at itsother end, means within the'casing connecting said contacts in circuit, said means comprising aswitch member supported by said terminal and a heating ele-'- ment located in close adjaoence to the thermostat in said pocket, the arrangementrbeing such that heat generated by said element is radiated and directly reflected against the thermostat by the walls of said pocket, causing the thermostat to deflect and move said terminal from its switch supporting position to release the switch and break the circuit;

3. A screw plug of the characterdescribed comprising a casing and contacts carried there- 'by exteriorlythereof, a thermostat within the casing, means within the casing connecting said contactsincircuit,saidmeans comprisinga element being located in close adiaeence to said thermostat, and means operable by the thermostat for releasing the switch to break said circuit; said switch comprising a'pivoting memher having a slot formed therein, a support affording an axis on which the slotted portion of the member is slidingly and pivotally mounted, a spring urging the member to pivot in the direction of contact, a cam carried by the member. and a fixed cam riding element for engagement by the cam, said cam being contoured to guide themember in a sliding movement on its axis as it is pivoted thereon, whereby the member contacts the terminalswhenit is pivoted in one direction and avoids them when it is reversely pivoted.

4. A pivot mechanism comprising a pivoting member having a slot formed therein, a support aifording an axis on which the slotted portion of the member is slidingly' and pivotaily mounted, a cam carried by the member,.and a fixed cam riding element for engagement by the cam,

said cam being contoured to guide the member inaslidingmovement onitsaxisasitispivoted thereon.

5. A pivot mechanism comprising a pivoting member having a slot formed therein, a support affording an axis on which the slotted portion 6.A screwplug 'of the character described,

comprising acasing and contacts carried thereconnecting said contacts-in circuit, said means by the thermostat, said switch comprising a pivoting member having a slot formed therein,

, by exteriorly thereof, means within thecasing 40 comprising a thermostat and a switchoperable a support affording an axis on which the slotted portion of the membei: is slidingly and pivotally mounted, a cam carried by the pivoting member, and a fixed cam riding element for engagement'by thecam,saidcambeingcontouredto guide the member in a sliding movement on its axis as it is pivoted thereon, whereby the memher is caused to make contact when pivoted in.

one direction and to avoid contact when reverse- 1y pivoted to reset the switch.

' ALBERT I. GRANT. 

